It wasn't uncommon for Katlin Watts to sit out during gym and recess. Her back, knees and tailbone hurt. Once, she missed a month and a half of school.

At 12, she had hip replacement surgery. Painkillers flowed through her veins.

"She was in pain to the point that she was screaming," said Latonya Watts, Katlin's mother.

Katlin, now 15, had sickle cell anemia, a genetic blood disease in which a person's red blood cells - normally round and agile - are instead crescent shaped, stiff and sticky. Because of their awkward shape, the blood cells catch, blocking oxygen flow to parts of the body. The disease can cause chest pain, organ damage and stroke. Severe cases can cut a person's life short by 30 years.

In the United States, the disease primarily affects African-Americans. Between 70,000 and 100,000 people have it. In North Carolina, at least 4,500 people live with it.

Today, Katlin is completely free of sickle cell disease. In 2009, she became the first sickle cell patient to receive a stem cell transplant in a clinical trial by the Levine Children's Hospital. Only about 10 sickle cell patients throughout the country have done a similar kind of transplant, her doctors said.

Two years later, Katlin is adjusting to life as an active teenager. And while she still has to undergo regular medical tests, she's in good health. And the longer she goes without further health issues, the doctors have told the Indian Trail family, the better her chances at avoiding complications as she grows older.

From the genes

If both parents have the sickle cell trait - even if they don't have the disease - there's a 25 percent chance their child will be born with it. No one in Latonya's or father Hiram's families suffered from the disease, so it came as a surprise.

As a result of a universal screening program in North Carolina that's been testing for sickle cell disease since 1994, they learned early that their daughter's disease was the product of genetic traits they had both unknowingly carried. About 1 in 12 African-Americans carries the trait.

Katlin's disease had its flare-ups but worsened considerably in 2007, when her hip problems began. Her parents started taking her once a month to get blood transfusions, which reduce the number of sickle cells in the body. For about three years, she took hydroxyurea, a common medication for sickle cell patients. But it stopped working and had unpleasant side effects.

She performed well in her classes, despite the interruptions. But at school, "some teachers didn't understand how intense the pain could be," Latonya said. When Katlin asked for pain medications, some teachers told her to wait. When she was cold - which can set off a pain crisis - a teacher once refused to allow her to get warmer clothes for outside, or go to the bathroom, Katlin said.

"It's hard not to get upset and feel sorry for yourself, but the sadder you make yourself, the more pain you'll be in," Katlin said.

She had a group of good friends, she said, but "catty girls would say the dumbest things."

Surgery and hope

Going to Camp Victory Junction, near Greensboro, for kids with physical disabilities helped her cope. In 2009, she became the Miracle Network Champion for North Carolina, a Wal-Mart-funded program that brings attention to children's hospitals.

But Katlin couldn't hide from the disease. In 2008, she had hip replacement surgery. A second surgery followed. Then the area got infected.

During the Children's Miracle Network tour, the Watts family met a girl with sickle cell disease who successfully received a bone marrow transplant. They went to Katlin's blood doctor, Daniel McMahon, the program director of pediatric hematology at Carolinas Medical Center, to find out more. He told them about the new transplant program that Dr. Andrew Gilman had launched at Levine Children's Hospital.

Searching for a match

Finding an exact match is one of the biggest challenges for sickle cell patients, who are supposed to get transplants before turning 16, when damage to the organs can reduce their chances of surviving.

Only 7 percent of sickle cell patients meet the criteria for getting a stem cell transplant, and the chances of finding a match are low.

Katlin's brother and sister weren't matches. The family tried bone marrow drives for a couple of months, even making pleas on television for African-American donors.

The Watts family decided to participate in Gilman's clinical trial. Gilman, who launched the transplant program at Levine Children's Hospital in 2008, was testing a special kind of treatment for patients with cancer and diseases of the blood and immune system - one that wouldn't require a donor to be an exact match.

With Gilman's treatment, Katlin's own father could be her donor.

A lifesaving machine

Something called a CliniMACS machine takes a donor's stem cells and extracts the T cells responsible for fighting off diseases.

"There are risks involved," Gilman said. "We only have transplant patients who are severely affected."

The risks include graft-versus-host disease, when a donor's immune system attacks the host's body. Health problems resulting from the disease - such as rashes, diarrhea or inflammation of the eyes, mouth and lungs - can last months or years.

But Katlin had few other options and her health problems were multiplying.

Before the transplant, Katlin spent 10 days receiving chemotherapy, a process that destroys the immune system and bone marrow so it can accept the donor's stem cells.

Hiram Watts, a 44-year-old systems engineer for Bank of America, sat for hours while a central line pumped blood from his neck. His blood was then shipped to San Francisco, where it went through the CliniMACS machine. A few days later, it was shipped back to Charlotte.

Gilman then sent Hiram's stem cells into Katlin's blood. She spent three weeks in the hospital after the transplant, the period it takes the donor stem cells to make enough blood cells.

Katlin was out of school for six months while her immune system slowly recovered.

Her mother, a special education teacher, quit her job and became Katlin's home-school teacher and full-time caregiver, administering her six intravenous medications. She cleaned the house for about four hours every day, wiping the walls, blinds and ceiling fans. She washed towels after each use.

When Katlin's then 11-year-old sister, Kendra, came home from school, she had to take off her shoes and clothes in the garage and take a shower. (And through it all, Katlin also remained protective of 12-year-old brother Keefer, who has autism.)

Thinking of the future

Since her transplant, Katlin has performed in plays, joined the church dance team and done community service through the 4-H Club at school. With the damage she has suffered, she may suffer pain or discomfort from time to time. This summer she underwent physical therapy, but is now just doing exercises at home.

This school year, she wants to be a cheerleader for the basketball team. It costs money, so she and her parents have agreed to split the cost 50-50. She's applying for part-time jobs at fast food restaurants.

Now in the 10th grade at the Central Academy of Technology and Art, she's focusing on medical science and taking Honors classes.

After high school, she wants to go to Duke University and become a specialty doctor. But she doesn't want to become a blood or cancer specialist, she said.

"I'd get too caught up in how they feel," she said. "Because I'd understand what they were going through."

Life after surgery has improved for Latonya and Hiram Watts, too. For the first time since their honeymoon, on July Fourth, the couple left North Carolina for a vacation. They spent four days in New Orleans, at the Essence Music Festival.

"We've taken little trips before but we were always worried about Katlin," Hiram Watts said. "There's not that fear anymore."